Provided by: jq_1.5+dfsg-1_amd64 bug


       jq - Command-line JSON processor


       jq [options...] filter [files...]

       jq  can  transform  JSON  in various ways, by selecting, iterating, reducing and otherwise
       mangling JSON documents. For instance, running the command jq  ´map(.price)  |  add´  will
       take an array of JSON objects as input and return the sum of their "price" fields.

       jq  can  accept  text  input  as  well, but by default, jq reads a stream of JSON entities
       (including numbers and other literals) from stdin. Whitespace is only needed  to  separate
       entities such as 1 and 2, and true and false. One or more files may be specified, in which
       case jq will read input from those instead.

       The options are described in the INVOKING JQ section; they mostly concern input and output
       formatting.  The  filter  is written in the jq language and specifies how to transform the
       input file or document.


       A jq program is a "filter": it takes an input, and produces an output. There are a lot  of
       builtin  filters for extracting a particular field of an object, or converting a number to
       a string, or various other standard tasks.

       Filters can be combined in various ways - you can pipe  the  output  of  one  filter  into
       another filter, or collect the output of a filter into an array.

       Some  filters  produce  multiple  results,  for instance there´s one that produces all the
       elements of its input array. Piping that filter into a second runs the second  filter  for
       each  element  of the array. Generally, things that would be done with loops and iteration
       in other languages are just done by gluing filters together in jq.

       It´s important to remember that every filter has an input and  an  output.  Even  literals
       like "hello" or 42 are filters - they take an input but always produce the same literal as
       output. Operations that combine two filters, like addition, generally feed the same  input
       to both and combine the results. So, you can implement an averaging filter as add / length
       - feeding the input array both to the add filter and the length filter and then performing
       the division.

       But that´s getting ahead of ourselves. :) Let´s start with something simpler:


       jq  filters  run  on  a  stream  of  JSON data. The input to jq is parsed as a sequence of
       whitespace-separated JSON values which are passed through the provided  filter  one  at  a
       time.  The  output(s)  of  the  filter are written to standard out, again as a sequence of
       whitespace-separated JSON data.

       Note: it is important to mind the shell´s quoting rules. As a general rule  it´s  best  to
       always  quote  (with  single-quote characters) the jq program, as too many characters with
       special meaning to jq are also shell meta-characters. For example, jq "foo" will  fail  on
       most  Unix  shells  because  that  will  be  the same as jq foo, which will generally fail
       because foo is not defined. When using the Windows command shell (cmd.exe)  it´s  best  to
       use double quotes around your jq program when given on the command-line (instead of the -f
       program-file option), but then double-quotes in the jq program need backslash escaping.

       You can affect how jq reads and writes  its  input  and  output  using  some  command-line

       •   --version:

           Output the jq version and exit with zero.

       •   --seq:

           Use  the application/json-seq MIME type scheme for separating JSON texts in jq´s input
           and output. This means that an ASCII RS (record separator) character is printed before
           each  value on output and an ASCII LF (line feed) is printed after every output. Input
           JSON texts that  fail  to  parse  are  ignored  (but  warned  about),  discarding  all
           subsequent input until the next RS. This more also parses the output of jq without the
           --seq option.

       •   --stream:

           Parse the input in streaming  fashion,  outputing  arrays  of  path  and  leaf  values
           (scalars  and  empty  arrays or empty objects). For example, "a" becomes [[],"a"], and
           [[],"a",["b"]] becomes [[0],[]], [[1],"a"], and [[1,0],"b"].

           This is useful for  processing  very  large  inputs.  Use  this  in  conjunction  with
           filtering and the reduce and foreach syntax to reduce large inputs incrementally.

       •   --slurp/-s:

           Instead of running the filter for each JSON object in the input, read the entire input
           stream into a large array and run the filter just once.

       •   --raw-input/-R:

           Don´t parse the input as JSON. Instead, each line of text is passed to the filter as a
           string.  If  combined with --slurp, then the entire input is passed to the filter as a
           single long string.

       •   --null-input/-n:

           Don´t read any input at all! Instead, the filter is run once using null as the  input.
           This  is  useful  when  using jq as a simple calculator or to construct JSON data from

       •   --compact-output / -c:

           By default, jq pretty-prints JSON output.  Using  this  option  will  result  in  more
           compact output by instead putting each JSON object on a single line.

       •   --tab:

           Use a tab for each indentation level instead of two spaces.

       •   --indent n:

           Use the given number of spaces (no more than 8) for indentation.

       •   --color-output / -C and --monochrome-output / -M:

           By  default,  jq  outputs  colored  JSON if writing to a terminal. You can force it to
           produce color even if writing to a pipe or a file using -C, and disable color with -M.

       •   --ascii-output / -a:

           jq usually outputs non-ASCII Unicode codepoints as UTF-8, even if the input  specified
           them  as  escape  sequences  (like  "\u03bc").  Using this option, you can force jq to
           produce pure ASCII output with every non-ASCII character replaced with the  equivalent
           escape sequence.

       •   --unbuffered

           Flush  the  output  after  each JSON object is printed (useful if you´re piping a slow
           data source into jq and piping jq´s output elsewhere).

       •   --sort-keys / -S:

           Output the fields of each object with the keys in sorted order.

       •   --raw-output / -r:

           With this option, if the filter´s result is a string then it will be written  directly
           to  standard output rather than being formatted as a JSON string with quotes. This can
           be useful for making jq filters talk to non-JSON-based systems.

       •   --join-output / -j:

           Like -r but jq won´t print a newline after each output.

       •   -f filename / --from-file filename:

           Read filter from the file rather than from a command line, like awk´s -f  option.  You
           can also use ´#´ to make comments.

       •   -Ldirectory / -L directory:

           Prepend  directory  to  the  search  list  for modules. If this option is used then no
           builtin search list is used. See the section on modules below.

       •   -e / --exit-status:

           Sets the exit status of jq to 0 if the last output values was neither false nor  null,
           1  if the last output value was either false or null, or 4 if no valid result was ever
           produced. Normally jq exits with 2 if there was any usage problem or system  error,  3
           if there was a jq program compile error, or 0 if the jq program ran.

       •   --arg name value:

           This  option  passes a value to the jq program as a predefined variable. If you run jq
           with --arg foo bar, then $foo is available in the program and  has  the  value  "bar".
           Note that value will be treated as a string, so --arg foo 123 will bind $foo to "123".

       •   --argjson name JSON-text:

           This option passes a JSON-encoded value to the jq program as a predefined variable. If
           you run jq with --argjson foo 123, then $foo is available in the program and  has  the
           value 123.

       •   --slurpfile variable-name filename:

           This  option  reads  all  the  JSON  texts in the named file and binds an array of the
           parsed JSON values to the given global variable. If you run jq with --argfile foo bar,
           then  $foo  is  available in the program and has an array whose elements correspond to
           the texts in the file named bar.

       •   --argfile variable-name filename:

           Do not use. Use --slurpfile instead.

           (This option is like --slurpfile, but when the file has just one text,  then  that  is
           used, else an array of texts is used as in --slurpfile.)

       •   --run-tests [filename]:

           Runs the tests in the given file or standard input. This must be the last option given
           and does not honor all preceding options. The input consists of comment  lines,  empty
           lines,  and  program  lines followed by one input line, as many lines of output as are
           expected (one per output), and a terminating empty  line.  Compilation  failure  tests
           start  with  a  line  containing  only "%%FAIL", then a line containing the program to
           compile, then a line containing an error message to compare to the actual.

           Be warned that this option can change backwards-incompatibly.


       The absolute simplest (and least interesting) filter is .. This is a filter that takes its
       input and produces it unchanged as output.

       Since  jq by default pretty-prints all output, this trivial program can be a useful way of
       formatting JSON output from, say, curl.

           jq ´.´
              "Hello, world!"
           => "Hello, world!"

       The simplest useful filter is .foo. When given a JSON object (aka dictionary or  hash)  as
       input, it produces the value at the key "foo", or null if there´s none present.

       If  the  key  contains special characters, you need to surround it with double quotes like
       this: ."foo$".

       A filter of the form is equivalent to .foo|.bar.

           jq ´.foo´
              {"foo": 42, "bar": "less interesting data"}
           => 42

           jq ´.foo´
              {"notfoo": true, "alsonotfoo": false}
           => null

           jq ´.["foo"]´
              {"foo": 42}
           => 42

       Just like .foo, but does not output even an error when . is not an array or an object.

           jq ´.foo?´
              {"foo": 42, "bar": "less interesting data"}
           => 42

           jq ´.foo?´
              {"notfoo": true, "alsonotfoo": false}
           => null

           jq ´.["foo"]?´
              {"foo": 42}
           => 42

           jq ´[.foo?]´
           => []

   .[<string>], .[2], .[10:15]
       You can also look up fields of an object using syntax  like  .["foo"]  (.foo  above  is  a
       shorthand  version  of this). This one works for arrays as well, if the key is an integer.
       Arrays are zero-based (like javascript), so .[2] returns the third element of the array.

       The .[10:15] syntax can be used to return a subarray of an array or substring of a string.
       The  array returned by .[10:15] will be of length 5, containing the elements from index 10
       (inclusive) to index 15 (exclusive). Either index may be negative (in which case it counts
       backwards  from the end of the array), or omitted (in which case it refers to the start or
       end of the array).

       The .[2] syntax can be used to return the element at the given index. Negative indices are
       allowed,  with -1 referring to the last element, -2 referring to the next to last element,
       and so on.

       The .foo syntax only works for simply keys i.e. keys that are all alphanumeric characters.
       .[<string>]  works  with keys that contain special characters such as colons and dots. For
       example .["foo::bar"] and .[""] work while .foo::bar and would not.

       The ? "operator" can also be used with the slice operator, as in .[10:15]?, which  outputs
       values where the inputs are slice-able.

           jq ´.[0]´
              [{"name":"JSON", "good":true}, {"name":"XML", "good":false}]
           => {"name":"JSON", "good":true}

           jq ´.[2]´
              [{"name":"JSON", "good":true}, {"name":"XML", "good":false}]
           => null

           jq ´.[2:4]´
           => ["c", "d"]

           jq ´.[2:4]´
           => "cd"

           jq ´.[:3]´
           => ["a", "b", "c"]

           jq ´.[-2:]´
           => ["d", "e"]

           jq ´.[-2]´
           => 2

       If  you  use  the  .[index] syntax, but omit the index entirely, it will return all of the
       elements of an array. Running .[] with the input [1,2,3] will produce the numbers as three
       separate results, rather than as a single array.

       You can also use this on an object, and it will return all the values of the object.

           jq ´.[]´
              [{"name":"JSON", "good":true}, {"name":"XML", "good":false}]
           => {"name":"JSON", "good":true}, {"name":"XML", "good":false}

           jq ´.[]´

           jq ´.[]´
              {"a": 1, "b": 1}
           => 1, 1

       Like .[], but no errors will be output if . is not an array or object.

       If  two  filters  are separated by a comma, then the input will be fed into both and there
       will be multiple outputs: first, all of the outputs produced by the left  expression,  and
       then  all  of the outputs produced by the right. For instance, filter .foo, .bar, produces
       both the "foo" fields and "bar" fields as separate outputs.

           jq ´.foo, .bar´
              {"foo": 42, "bar": "something else", "baz": true}
           => 42, "something else"

           jq ´.user, .projects[]´
              {"user":"stedolan", "projects": ["jq", "wikiflow"]}
           => "stedolan", "jq", "wikiflow"

           jq ´.[4,2]´
           => "e", "c"

       The | operator combines two filters by feeding the output(s) of the one on the  left  into
       the  input of the one on the right. It´s pretty much the same as the Unix shell´s pipe, if
       you´re used to that.

       If the one on the left produces multiple results, the one on the right  will  be  run  for
       each  of  those  results.  So, the expression .[] | .foo retrieves the "foo" field of each
       element of the input array.

           jq ´.[] | .name´
              [{"name":"JSON", "good":true}, {"name":"XML", "good":false}]
           => "JSON", "XML"


       jq supports the same set of datatypes  as  JSON  -  numbers,  strings,  booleans,  arrays,
       objects (which in JSON-speak are hashes with only string keys), and "null".

       Booleans,  null,  strings and numbers are written the same way as in javascript. Just like
       everything else in jq, these simple values take an input and produce an output - 42  is  a
       valid jq expression that takes an input, ignores it, and returns 42 instead.

   Array construction - []
       As  in JSON, [] is used to construct arrays, as in [1,2,3]. The elements of the arrays can
       be any jq expression. All of the results produced by all of the expressions are  collected
       into one big array. You can use it to construct an array out of a known quantity of values
       (as in [.foo, .bar, .baz]) or to "collect" all the results of a filter into an  array  (as
       in [.items[].name])

       Once  you  understand  the  "," operator, you can look at jq´s array syntax in a different
       light: the expression [1,2,3] is not using a built-in syntax for  comma-separated  arrays,
       but  is  instead applying the [] operator (collect results) to the expression 1,2,3 (which
       produces three different results).

       If you have a filter X that produces four results, then the expression [X] will produce  a
       single result, an array of four elements.

           jq ´[.user, .projects[]]´
              {"user":"stedolan", "projects": ["jq", "wikiflow"]}
           => ["stedolan", "jq", "wikiflow"]

   Objects - {}
       Like  JSON,  {} is for constructing objects (aka dictionaries or hashes), as in: {"a": 42,
       "b": 17}.

       If the keys are "sensible" (all alphabetic characters), then the quotes can be  left  off.
       The value can be any expression (although you may need to wrap it in parentheses if it´s a
       complicated one), which gets applied to the {} expression´s input (remember,  all  filters
       have an input and an output).

           {foo: .bar}

       will  produce  the  JSON object {"foo": 42} if given the JSON object {"bar":42, "baz":43}.
       You can use this to select particular fields of an object: if the input is an object  with
       "user",  "title", "id", and "content" fields and you just want "user" and "title", you can

           {user: .user, title: .title}

       Because that´s so common, there´s a shortcut syntax: {user, title}.

       If one of the  expressions  produces  multiple  results,  multiple  dictionaries  will  be
       produced. If the input´s

           {"user":"stedolan","titles":["JQ Primer", "More JQ"]}

       then the expression

           {user, title: .titles[]}

       will produce two outputs:

           {"user":"stedolan", "title": "JQ Primer"}
           {"user":"stedolan", "title": "More JQ"}

       Putting  parentheses  around the key means it will be evaluated as an expression. With the
       same input as above,

           {(.user): .titles}


           {"stedolan": ["JQ Primer", "More JQ"]}

           jq ´{user, title: .titles[]}´
              {"user":"stedolan","titles":["JQ Primer", "More JQ"]}
           => {"user":"stedolan", "title": "JQ Primer"}, {"user":"stedolan", "title": "More JQ"}

           jq ´{(.user): .titles}´
              {"user":"stedolan","titles":["JQ Primer", "More JQ"]}
           => {"stedolan": ["JQ Primer", "More JQ"]}


       Some jq operator (for instance, +) do different things depending  on  the  type  of  their
       arguments  (arrays,  numbers,  etc.). However, jq never does implicit type conversions. If
       you try to add a string to an object you´ll get an error message and no result.

   Addition - +
       The operator + takes two filters, applies them both  to  the  same  input,  and  adds  the
       results together. What "adding" means depends on the types involved:

       •   Numbers are added by normal arithmetic.

       •   Arrays are added by being concatenated into a larger array.

       •   Strings are added by being joined into a larger string.

       •   Objects  are  added  by  merging, that is, inserting all the key-value pairs from both
           objects into a single combined object. If both objects contain a value  for  the  same
           key, the object on the right of the + wins. (For recursive merge use the * operator.)

       null can be added to any value, and returns the other value unchanged.

           jq ´.a + 1´
              {"a": 7}
           => 8

           jq ´.a + .b´
              {"a": [1,2], "b": [3,4]}
           => [1,2,3,4]

           jq ´.a + null´
              {"a": 1}
           => 1

           jq ´.a + 1´
           => 1

           jq ´{a: 1} + {b: 2} + {c: 3} + {a: 42}´
           => {"a": 42, "b": 2, "c": 3}

   Subtraction - -
       As  well as normal arithmetic subtraction on numbers, the - operator can be used on arrays
       to remove all occurrences of the second array´s elements from the first array.

           jq ´4 - .a´
           => 1

           jq ´. - ["xml", "yaml"]´
              ["xml", "yaml", "json"]
           => ["json"]

   Multiplication, division, modulo - *, /, and %
       These infix operators behave as expected when given two numbers. Division by  zero  raises
       an error. x % y computes x modulo y.

       Multiplying  a  string  by  a  number  produces the concatenation of that string that many
       times. "x" * 0 produces null.

       Dividing a string by another splits the first using the second as separators.

       Multiplying two objects will merge them recursively: this works like addition but if  both
       objects  contain  a value for the same key, and the values are objects, the two are merged
       with the same strategy.

           jq ´10 / . * 3´
           => 6

           jq ´. / ", "´
              "a, b,c,d, e"
           => ["a","b,c,d","e"]

           jq ´{"k": {"a": 1, "b": 2}} * {"k": {"a": 0,"c": 3}}´
           => {"k": {"a": 0, "b": 2, "c": 3}}

           jq ´.[] | (1 / .)?´
           => 1, -1

       The builtin function length gets the length of various different types of value:

       •   The length of a string is the number of Unicode codepoints it contains (which will  be
           the same as its JSON-encoded length in bytes if it´s pure ASCII).

       •   The length of an array is the number of elements.

       •   The length of an object is the number of key-value pairs.

       •   The length of null is zero.

           jq ´.[] | length´ [[1,2], "string", {"a":2}, null] => 2, 6, 1, 0

   keys, keys_unsorted
       The builtin function keys, when given an object, returns its keys in an array.

       The  keys  are  sorted  "alphabetically", by unicode codepoint order. This is not an order
       that makes particular sense in any particular language, but you can count on it being  the
       same for any two objects with the same set of keys, regardless of locale settings.

       When  keys  is  given  an array, it returns the valid indices for that array: the integers
       from 0 to length-1.

       The keys_unsorted function is just like keys, but if the input is an object then the  keys
       will not be sorted, instead the keys will roughly be in insertion order.

           jq ´keys´
              {"abc": 1, "abcd": 2, "Foo": 3}
           => ["Foo", "abc", "abcd"]

           jq ´keys´
           => [0,1,2]

       The  builtin function has returns whether the input object has the given key, or the input
       array has an element at the given index.

       has($key) has the same effect as checking whether $key is a member of the  array  returned
       by keys, although has will be faster.

           jq ´map(has("foo"))´
              [{"foo": 42}, {}]
           => [true, false]

           jq ´map(has(2))´
              [[0,1], ["a","b","c"]]
           => [false, true]

       The  builtin  function in returns the input key is in the given object, or the input index
       corresponds to an element in the given array. It is, essentially, an inversed  version  of

           jq ´.[] | in({"foo": 42})´
              ["foo", "bar"]
           => true, false

           jq ´map(in([0,1]))´
              [2, 0]
           => [false, true]

       Outputs array representations of the given path expression in .. The outputs are arrays of
       strings (keys in objects0 and/or numbers (array indices.

       Path expressions are jq expressions like .a, but also .[]. There are  two  types  of  path
       expressions:  ones that can match exactly, and ones that cannot. For example, .a.b.c is an
       exact match path expression, while .a[].b is not.

       path(exact_path_expression) will produce the array representation of the  path  expression
       even if it does not exist in ., if . is null or an array or an object.

       path(pattern)  will  produce  array  representations  of the paths matching pattern if the
       paths exist in ..

       Note that the path expressions are not different from normal expressions.  The  expression
       path(..|select(type=="boolean"))  outputs  all  the paths to boolean values in ., and only
       those paths.

           jq ´path(.a[0].b)´
           => ["a",0,"b"]

           jq ´[path(..)]´
           => [[],["a"],["a",0],["a",0,"b"]]

       The builtin function del removes a key and its corresponding value from an object.

           jq ´del(.foo)´
              {"foo": 42, "bar": 9001, "baz": 42}
           => {"bar": 9001, "baz": 42}

           jq ´del(.[1, 2])´
              ["foo", "bar", "baz"]
           => ["foo"]

   to_entries, from_entries, with_entries
       These functions convert between an object and an array of key-value pairs.  If  to_entries
       is  passed  an  object,  then  for each k: v entry in the input, the output array includes
       {"key": k, "value": v}.

       from_entries does the opposite  conversion,  and  with_entries(foo)  is  a  shorthand  for
       to_entries  |  map(foo)  |  from_entries,  useful for doing some operation to all keys and
       values of an object. from_entries accepts key, Key, Name, value and Value as keys.

           jq ´to_entries´
              {"a": 1, "b": 2}
           => [{"key":"a", "value":1}, {"key":"b", "value":2}]

           jq ´from_entries´
              [{"key":"a", "value":1}, {"key":"b", "value":2}]
           => {"a": 1, "b": 2}

           jq ´with_entries(.key |= "KEY_" + .)´
              {"a": 1, "b": 2}
           => {"KEY_a": 1, "KEY_b": 2}

       The function select(foo) produces its input unchanged if foo returns true for that  input,
       and produces no output otherwise.

       It´s useful for filtering lists: [1,2,3] | map(select(. >= 2)) will give you [2,3].

           jq ´map(select(. >= 2))´
           => [5,3,7]

           jq ´.[] | select(.id == "second")´
              [{"id": "first", "val": 1}, {"id": "second", "val": 2}]
           => {"id": "second", "val": 2}

   arrays,  objects,  iterables,  booleans,  numbers,  normals,  finites, strings, nulls, values,
       These built-ins select  only  inputs  that  are  arrays,  objects,  iterables  (arrays  or
       objects),  booleans,  numbers,  normal  numbers,  finite  numbers, strings, null, non-null
       values, and non-iterables, respectively.

           jq ´.[]|numbers´
           => 1

       empty returns no results. None at all. Not even null.

       It´s useful on occasion. You´ll know if you need it :)

           jq ´1, empty, 2´
           => 1, 2

           jq ´[1,2,empty,3]´
           => [1,2,3]

       Produces an error, just like .a applied to values other than null and objects  would,  but
       with the given message as the error´s value.

       Produces  an  object with a "file" key and a "line" key, with the filename and line number
       where $__loc__ occurs, as values.

           jq ´try error("\($__loc__)") catch .´
           => "{\"file\":\"<top-level>\",\"line\":1}"

   map(x), map_values(x)
       For any filter x, map(x) will run that filter for each element of  the  input  array,  and
       produce  the  outputs  a  new  array.  map(.+1) will increment each element of an array of

       Similarly, map_values(x) will run that filter for each element,  but  it  will  return  an
       object when an object is passed.

       map(x)  is  equivalent  to  [.[]  |  x].  In  fact,  this  is how it´s defined. Similarly,
       map_values(x) is defined as .[] |= x.

           jq ´map(.+1)´
           => [2,3,4]

           jq ´map_values(.+1)´
              {"a": 1, "b": 2, "c": 3}
           => {"a": 2, "b": 3, "c": 4}

   paths, paths(node_filter), leaf_paths
       paths outputs the paths to all the elements in its input (except it does  not  output  the
       empty list, representing . itself).

       paths(f)  outputs  the  paths  to  any values for which f is true. That is, paths(numbers)
       outputs the paths to all numeric values.

       leaf_paths is an alias of paths(scalars); leaf_paths is deprecated and will be removed  in
       the next major release.

           jq ´[paths]´
           => [[0],[1],[1,0],[1,1],[1,1,"a"]]

           jq ´[paths(scalars)]´
           => [[0],[1,1,"a"]]

       The  filter  add takes as input an array, and produces as output the elements of the array
       added together. This might mean summed, concatenated or merged depending on the  types  of
       the  elements  of  the  input  array  - the rules are the same as those for the + operator
       (described above).

       If the input is an empty array, add returns null.

           jq ´add´
           => "abc"

           jq ´add´
              [1, 2, 3]
           => 6

           jq ´add´
           => null

   any, any(condition), any(generator; condition)
       The filter any takes as input an array of boolean values, and produces true as  output  if
       any of the the elements of the array is true.

       If the input is an empty array, any returns false.

       The any(condition) form applies the given condition to the elements of the input array.

       The  any(generator;  condition) form applies the given condition to all the outputs of the
       given generator.

           jq ´any´
              [true, false]
           => true

           jq ´any´
              [false, false]
           => false

           jq ´any´
           => false

   all, all(condition), all(generator; condition)
       The filter all takes as input an array of boolean values, and produces true as  output  if
       all of the the elements of the array are true.

       The all(condition) form applies the given condition to the elements of the input array.

       The  all(generator;  condition) form applies the given condition to all the outputs of the
       given generator.

       If the input is an empty array, all returns true.

           jq ´all´
              [true, false]
           => false

           jq ´all´
              [true, true]
           => true

           jq ´all´
           => true

   [Requires 1.5] flatten, flatten(depth)
       The filter flatten takes as input an array of nested arrays, and produces a flat array  in
       which all arrays inside the original array have been recursively replaced by their values.
       You can pass an argument to it to specify how many levels of nesting to flatten.

       flatten(2) is like flatten, but going only up to two levels deep.

           jq ´flatten´
              [1, [2], [[3]]]
           => [1, 2, 3]

           jq ´flatten(1)´
              [1, [2], [[3]]]
           => [1, 2, [3]]

           jq ´flatten´
           => []

           jq ´flatten´
              [{"foo": "bar"}, [{"foo": "baz"}]]
           => [{"foo": "bar"}, {"foo": "baz"}]

   range(upto), range(from;upto) range(from;upto;by)
       The range function produces a range of numbers. range(4;10) produces  6  numbers,  from  4
       (inclusive)  to  10  (exclusive).  The  numbers  are  produced  as  separate  outputs. Use
       [range(4;10)] to get a range as an array.

       The one argument form generates numbers from 0 to the given number, with an  increment  of

       The two argument form generates numbers from from to upto with an increment of 1.

       The three argument form generates numbers from to upto with an increment of by.

           jq ´range(2;4)´
           => 2, 3

           jq ´[range(2;4)]´
           => [2,3]

           jq ´[range(4)]´
           => [0,1,2,3]

           jq ´[range(0;10;3)]´
           => [0,3,6,9]

           jq ´[range(0;10;-1)]´
           => []

           jq ´[range(0;-5;-1)]´
           => [0,-1,-2,-3,-4]

       The floor function returns the floor of its numeric input.

           jq ´floor´
           => 3

       The sqrt function returns the square root of its numeric input.

           jq ´sqrt´
           => 3

       The  tonumber  function  parses its input as a number. It will convert correctly-formatted
       strings to their numeric equivalent, leave numbers alone, and give an error on  all  other

           jq ´.[] | tonumber´
              [1, "1"]
           => 1, 1

       The  tostring  function  prints its input as a string. Strings are left unchanged, and all
       other values are JSON-encoded.

           jq ´.[] | tostring´
              [1, "1", [1]]
           => "1", "1", "[1]"

       The type function returns the type of its argument as a string,  which  is  one  of  null,
       boolean, number, string, array or object.

           jq ´map(type)´
              [0, false, [], {}, null, "hello"]
           => ["number", "boolean", "array", "object", "null", "string"]

   infinite, nan, isinfinite, isnan, isfinite, isnormal
       Some  arithmetic  operations  can  yield  infinities  and "not a number" (NaN) values. The
       isinfinite builtin returns true if its input is infinite. The isnan builtin  returns  true
       if  its  input  is  a NaN. The infinite builtin returns a positive infinite value. The nan
       builtin returns a NaN. The isnormal builtin returns true if its input is a normal number.

       Note that division by zero raises an error.

       Currently most arithmetic operations operating on infinities, NaNs, and sub-normals do not
       raise errors.

           jq ´.[] | (infinite * .) < 0´
              [-1, 1]
           => true, false

           jq ´infinite, nan | type´
           => "number", "number"

   sort, sort_by(path_expression)
       The  sort  functions  sorts  its  input,  which must be an array. Values are sorted in the
       following order:

       •   nullfalsetrue

       •   numbers

       •   strings, in alphabetical order (by unicode codepoint value)

       •   arrays, in lexical order

       •   objects

       The ordering for objects is a little complex: first they´re compared  by  comparing  their
       sets  of keys (as arrays in sorted order), and if their keys are equal then the values are
       compared key by key.

       sort may be used to sort by a particular field of an object, or by applying any jq filter.

       sort_by(foo) compares two elements by comparing the result of foo on each element.

           jq ´sort´
           => [null,3,6,8]

           jq ´sort_by(.foo)´
              [{"foo":4, "bar":10}, {"foo":3, "bar":100}, {"foo":2, "bar":1}]
           => [{"foo":2, "bar":1}, {"foo":3, "bar":100}, {"foo":4, "bar":10}]

       group_by(.foo) takes as input an array, groups the elements having  the  same  .foo  field
       into  separate  arrays,  and  produces  all of these arrays as elements of a larger array,
       sorted by the value of the .foo field.

       Any jq expression, not just a field access, may be used in  place  of  .foo.  The  sorting
       order is the same as described in the sort function above.

           jq ´group_by(.foo)´
              [{"foo":1, "bar":10}, {"foo":3, "bar":100}, {"foo":1, "bar":1}]
           => [[{"foo":1, "bar":10}, {"foo":1, "bar":1}], [{"foo":3, "bar":100}]]

   min, max, min_by(path_exp), max_by(path_exp)
       Find the minimum or maximum element of the input array.

       The  min_by(path_exp)  and  max_by(path_exp)  functions  allow you to specify a particular
       field or property to examine, e.g. min_by(.foo) finds the object  with  the  smallest  foo

           jq ´min´
           => 2

           jq ´max_by(.foo)´
              [{"foo":1, "bar":14}, {"foo":2, "bar":3}]
           => {"foo":2, "bar":3}

   unique, unique_by(path_exp)
       The unique function takes as input an array and produces an array of the same elements, in
       sorted order, with duplicates removed.

       The unique_by(path_exp) function will keep only one element for  each  value  obtained  by
       applying  the  argument. Think of it as making an array by taking one element out of every
       group produced by group.

           jq ´unique´
           => [1,2,3,5]

           jq ´unique_by(.foo)´
              [{"foo": 1, "bar": 2}, {"foo": 1, "bar": 3}, {"foo": 4, "bar": 5}]
           => [{"foo": 1, "bar": 2}, {"foo": 4, "bar": 5}]

           jq ´unique_by(length)´
              ["chunky", "bacon", "kitten", "cicada", "asparagus"]
           => ["bacon", "chunky", "asparagus"]

       This function reverses an array.

           jq ´reverse´
           => [4,3,2,1]

       The filter contains(b) will produce true if b is completely contained within the input.  A
       string  B  is contained in a string A if B is a substring of A. An array B is contained in
       an array A if all elements in B are contained  in  any  element  in  A.  An  object  B  is
       contained  in  object A if all of the values in B are contained in the value in A with the
       same key. All other types are assumed to be contained in each other if they are equal.

           jq ´contains("bar")´
           => true

           jq ´contains(["baz", "bar"])´
              ["foobar", "foobaz", "blarp"]
           => true

           jq ´contains(["bazzzzz", "bar"])´
              ["foobar", "foobaz", "blarp"]
           => false

           jq ´contains({foo: 12, bar: [{barp: 12}]})´
              {"foo": 12, "bar":[1,2,{"barp":12, "blip":13}]}
           => true

           jq ´contains({foo: 12, bar: [{barp: 15}]})´
              {"foo": 12, "bar":[1,2,{"barp":12, "blip":13}]}
           => false

       Outputs an array containing the indices in . where s occurs. The input may be an array, in
       which  case if s is an array then the indices output will be those where all elements in .
       match those of s.

           jq ´indices(", ")´
              "a,b, cd, efg, hijk"
           => [3,7,12]

           jq ´indices(1)´
           => [1,3,5]

           jq ´indices([1,2])´
           => [1,8]

   index(s), rindex(s)
       Outputs the index of the first (index) or last (rindex) occurrence of s in the input.

           jq ´index(", ")´
              "a,b, cd, efg, hijk"
           => 3

           jq ´rindex(", ")´
              "a,b, cd, efg, hijk"
           => 12

       The filter inside(b) will produce true if the input is completely contained within  b.  It
       is, essentially, an inversed version of contains.

           jq ´inside("foobar")´
           => true

           jq ´inside(["foobar", "foobaz", "blarp"])´
              ["baz", "bar"]
           => true

           jq ´inside(["foobar", "foobaz", "blarp"])´
              ["bazzzzz", "bar"]
           => false

           jq ´inside({"foo": 12, "bar":[1,2,{"barp":12, "blip":13}]})´
              {"foo": 12, "bar": [{"barp": 12}]}
           => true

           jq ´inside({"foo": 12, "bar":[1,2,{"barp":12, "blip":13}]})´
              {"foo": 12, "bar": [{"barp": 15}]}
           => false

       Outputs true if . starts with the given string argument.

           jq ´[.[]|startswith("foo")]´
              ["fo", "foo", "barfoo", "foobar", "barfoob"]
           => [false, true, false, true, false]

       Outputs true if . ends with the given string argument.

           jq ´[.[]|endswith("foo")]´
              ["foobar", "barfoo"]
           => [false, true]

   combinations, combinations(n)
       Outputs  all  combinations  of  the elements of the arrays in the input array. If given an
       argument n, it outputs all combinations of n repetitions of the input array.

           jq ´combinations´
              [[1,2], [3, 4]]
           => [1, 3], [1, 4], [2, 3], [2, 4]

           jq ´combinations(2)´
              [0, 1]
           => [0, 0], [0, 1], [1, 0], [1, 1]

       Outputs its input with the given prefix string removed, if it starts with it.

           jq ´[.[]|ltrimstr("foo")]´
              ["fo", "foo", "barfoo", "foobar", "afoo"]
           => ["fo","","barfoo","bar","afoo"]

       Outputs its input with the given suffix string removed, if it ends with it.

           jq ´[.[]|rtrimstr("foo")]´
              ["fo", "foo", "barfoo", "foobar", "foob"]
           => ["fo","","bar","foobar","foob"]

       Converts an input string into an array of the string´s codepoint numbers.

           jq ´explode´
           => [102,111,111,98,97,114]

       The inverse of explode.

           jq ´implode´
              [65, 66, 67]
           => "ABC"

       Splits an input string on the separator argument.

           jq ´split(", ")´
              "a, b,c,d, e, "
           => ["a","b,c,d","e",""]

       Joins the array of elements given as input, using the argument as  separator.  It  is  the
       inverse  of  split:  that  is,  running  split("foo")  | join("foo") over any input string
       returns said input string.

           jq ´join(", ")´
           => "a, b,c,d, e"

   ascii_downcase, ascii_upcase
       Emit a copy of the input string with its alphabetic characters (a-z and A-Z) converted  to
       the specified case.

   while(cond; update)
       The  while(cond; update) function allows you to repeatedly apply an update to . until cond
       is false.

       Note that while(cond; update) is internally defined as a recursive jq function.  Recursive
       calls  within  while  will  not  consume  additional memory if update produces at most one
       output for each input. See advanced topics below.

           jq ´[while(.<100; .*2)]´
           => [1,2,4,8,16,32,64]

   until(cond; next)
       The until(cond; next) function  allows  you  to  repeatedly  apply  the  expression  next,
       initially  to  . then to its own output, until cond is true. For example, this can be used
       to implement a factorial function (see below).

       Note that until(cond; next) is internally defined as a recursive  jq  function.  Recursive
       calls  within  until()  will  not  consume  additional memory if next produces at most one
       output for each input. See advanced topics below.

           jq ´[.,1]|until(.[0] < 1; [.[0] - 1, .[1] * .[0]])|.[1]´
           => 24

   recurse(f), recurse, recurse(f; condition), recurse_down
       The recurse(f) function allows you to search through a recursive  structure,  and  extract
       interesting data from all levels. Suppose your input represents a filesystem:

           {"name": "/", "children": [
             {"name": "/bin", "children": [
               {"name": "/bin/ls", "children": []},
               {"name": "/bin/sh", "children": []}]},
             {"name": "/home", "children": [
               {"name": "/home/stephen", "children": [
                 {"name": "/home/stephen/jq", "children": []}]}]}]}

       Now  suppose you want to extract all of the filenames present. You need to retrieve .name,
       .children[].name, .children[].children[].name, and so on. You can do this with:

           recurse(.children[]) | .name

       When called without an argument, recurse is equivalent to recurse(.[]?).

       recurse(f) is identical to recurse(f; . != null) and can be used  without  concerns  about
       recursion depth.

       recurse(f;  condition)  is  a  generator which begins by emitting . and then emits in turn
       .|f, .|f|f, .|f|f|f, ... so long as  the  computed  value  satisfies  the  condition.  For
       example, to generate all the integers, at least in principle, one could write recurse(.+1;

       For legacy reasons, recurse_down exists as an alias to calling recurse without  arguments.
       This alias is considered deprecated and will be removed in the next major release.

       The  recursive  calls in recurse will not consume additional memory whenever f produces at
       most a single output for each input.

           jq ´recurse(.foo[])´
              {"foo":[{"foo": []}, {"foo":[{"foo":[]}]}]}
           => {"foo":[{"foo":[]},{"foo":[{"foo":[]}]}]}, {"foo":[]}, {"foo":[{"foo":[]}]}, {"foo":[]}

           jq ´recurse´
           => {"a":0,"b":[1]}, 0, [1], 1

           jq ´recurse(. * .; . < 20)´
           => 2, 4, 16

       Short-hand for recurse without arguments. This  is  intended  to  resemble  the  XPath  //
       operator.  Note  that  ..a  does  not  work; use ..|a instead. In the example below we use
       ..|.a? to find all the values of object keys "a" in any object found "below" ..

           jq ´..|.a?´
           => 1

       Outputs an object representing jq´s environment.

           jq ´env.PAGER´
           => "less"

       Transpose a possibly jagged matrix (an array of arrays). Rows are padded with nulls so the
       result is always rectangular.

           jq ´transpose´
              [[1], [2,3]]
           => [[1,2],[null,3]]

       bsearch(x)  conducts  a binary search for x in the input array. If the input is sorted and
       contains x, then bsearch(x) will return its index in the array; otherwise, if the array is
       sorted,  it will return (-1 - ix) where ix is an insertion point such that the array would
       still be sorted after the insertion of x at ix. If the array  is  not  sorted,  bsearch(x)
       will return an integer that is probably of no interest.

           jq ´bsearch(0)´
           => 0

           jq ´bsearch(0)´
           => -1

           jq ´bsearch(4) as $ix | if $ix < 0 then .[-(1+$ix)] = 4 else . end´
           => [1,2,3,4]

   String interpolation - \(foo)
       Inside  a  string, you can put an expression inside parens after a backslash. Whatever the
       expression returns will be interpolated into the string.

           jq ´"The input was \(.), which is one less than \(.+1)"´
           => "The input was 42, which is one less than 43"

   Convert to/from JSON
       The tojson and fromjson builtins dump values as  JSON  texts  or  parse  JSON  texts  into
       values,  respectively.  The  tojson builtin differs from tostring in that tostring returns
       strings unmodified, while tojson encodes strings as JSON strings.

           jq ´[.[]|tostring]´
              [1, "foo", ["foo"]]
           => ["1","foo","[\"foo\"]"]

           jq ´[.[]|tojson]´
              [1, "foo", ["foo"]]
           => ["1","\"foo\"","[\"foo\"]"]

           jq ´[.[]|tojson|fromjson]´
              [1, "foo", ["foo"]]
           => [1,"foo",["foo"]]

   Format strings and escaping
       The @foo syntax is used to format and escape strings, which is useful for  building  URLs,
       documents  in  a  language like HTML or XML, and so forth. @foo can be used as a filter on
       its own, the possible escapings are:


              Calls tostring, see that function for details.


              Serializes the input as JSON.


              Applies HTML/XML  escaping,  by  mapping  the  characters  <>&´"  to  their  entity
              equivalents &lt;, &gt;, &amp;, &apos;, &quot;.


              Applies percent-encoding, by mapping all reserved URI characters to a %XX sequence.


              The  input  must  be  an  array,  and  it is rendered as CSV with double quotes for
              strings, and quotes escaped by repetition.


              The input must be an array, and it is rendered as TSV (tab-separated values).  Each
              input  array will be printed as a single line. Fields are separated by a single tab
              (ascii 0x09). Input  characters  line-feed  (ascii  0x0a),  carriage-return  (ascii
              0x0d),  tab  (ascii  0x09)  and  backslash  (ascii  0x5c)  will be output as escape
              sequences \n, \r, \t, \\ respectively.


              The input is escaped suitable for use in a command-line for a POSIX shell.  If  the
              input is an array, the output will be a series of space-separated strings.


              The input is converted to base64 as specified by RFC 4648.

       This  syntax  can  be combined with string interpolation in a useful way. You can follow a
       @foo token with a string literal. The contents of the string literal will not be  escaped.
       However, all interpolations made inside that string literal will be escaped. For instance,

           @uri "\(.search)"

       will produce the following output for the input {"search":"what is jq?"}:


       Note  that  the slashes, question mark, etc. in the URL are not escaped, as they were part
       of the string literal.

           jq ´@html´
              "This works if x < y"
           => "This works if x &lt; y"

           jq ´@sh "echo \(.)"´
              "O´Hara´s Ale"
           => "echo ´O´\\´´Hara´\\´´s Ale´"

       jq provides some basic date handling functionality, with  some  high-level  and  low-level
       builtins. In all cases these builtins deal exclusively with time in UTC.

       The fromdateiso8601 builtin parses datetimes in the ISO 8601 format to a number of seconds
       since the Unix epoch (1970-01-01T00:00:00Z). The todateiso8601 builtin does the inverse.

       The fromdate builtin parses datetime strings. Currently fromdate only  supports  ISO  8601
       datetime  strings,  but  in  the  future it will attempt to parse datetime strings in more

       The todate builtin is an alias for todateiso8601.

       The now builtin outputs the current time, in seconds since the Unix epoch.

       Low-level jq interfaces to the C-library  time  functions  are  also  provided:  strptime,
       strftime,  mktime, and gmtime. Refer to your host operating system´s documentation for the
       format strings used by strptime and strftime.  Note:  these  are  not  necessarily  stable
       interfaces in jq, particularly as to their localization functionality.

       The gmtime builtin consumes a number of seconds since the Unix epoch and outputs a "broken
       down time" representation of time as an array of numbers representing (in this order): the
       year, the month (zero-based), the day of the month, the hour of the day, the minute of the
       hour, the second of the minute, the day of the week, and  the  day  of  the  year  --  all
       one-based unless otherwise stated.

       The  mktime  builtin  consumes "broken down time" representations of time output by gmtime
       and strptime.

       The strptime(fmt) builtin parses input strings matching the fmt argument. The output is in
       the "broken down time" representation consumed by gmtime and output by mktime.

       The strftime(fmt) builtin formats a time with the given format.

       The  format  strings  for  strptime  and  strftime  are  described  in  typical  C library
       documentation. The format string for ISO 8601 datetime is "%Y-%m-%dT%H:%M:%SZ".

       jq may not support some or all of this date functionality on some systems.

           jq ´fromdate´
           => 1425599507

           jq ´strptime("%Y-%m-%dT%H:%M:%SZ")´
           => [2015,2,5,23,51,47,4,63]

           jq ´strptime("%Y-%m-%dT%H:%M:%SZ")|mktime´
           => 1425599507


   ==, !=
       The expression ´a == b´ will produce ´true´ if the result of a and b are equal  (that  is,
       if they represent equivalent JSON documents) and ´false´ otherwise. In particular, strings
       are never considered equal to numbers. If you´re coming from Javascript, jq´s ==  is  like
       Javascript´s  ===  - considering values equal only when they have the same type as well as
       the same value.

       != is "not equal", and ´a != b´ returns the opposite value of ´a == b´

           jq ´.[] == 1´
              [1, 1.0, "1", "banana"]
           => true, true, false, false

       if A then B else C end will act the same as B if A produces a value other  than  false  or
       null, but act the same as C otherwise.

       Checking for false or null is a simpler notion of "truthiness" than is found in Javascript
       or Python, but it means that you´ll sometimes have to be more explicit about the condition
       you want: you can´t test whether, e.g. a string is empty using if .name then A else B end,
       you´ll need something more like if (.name | length) > 0 then A else B end instead.

       If the condition A produces multiple results, it is considered  "true"  if  any  of  those
       results is not false or null. If it produces zero results, it´s considered false.

       More cases can be added to an if using elif A then B syntax.

           jq ´if . == 0 then

       "zero" elif . == 1 then "one" else "many" end´ 2 => "many"

   >, >=, <=, <
       The  comparison operators >, >=, <=, < return whether their left argument is greater than,
       greater than or equal to, less than  or  equal  to  or  less  than  their  right  argument

       The ordering is the same as that described for sort, above.

           jq ´. < 5´
           => true

       jq  supports the normal Boolean operators and/or/not. They have the same standard of truth
       as if expressions - false and null are considered "false values", and anything else  is  a
       "true value".

       If  an  operand  of  one of these operators produces multiple results, the operator itself
       will produce a result for each input.

       not is in fact a builtin function rather than an operator, so it is called as a filter  to
       which things can be piped rather than with special syntax, as in .foo and .bar | not.

       These three only produce the values "true" and "false", and so are only useful for genuine
       Boolean   operations,   rather    than    the    common    Perl/Python/Ruby    idiom    of
       "value_that_may_be_null or default". If you want to use this form of "or", picking between
       two values rather than evaluating a condition, see the "//" operator below.

           jq ´42 and "a string"´
           => true

           jq ´(true, false) or false´
           => true, false

           jq ´(true, true) and (true, false)´
           => true, false, true, false

           jq ´[true, false | not]´
           => [false, true]

   Alternative operator - //
       A filter of the form a // b produces the same results as a, if a  produces  results  other
       than false and null. Otherwise, a // b produces the same results as b.

       This  is  useful  for  providing defaults: .foo // 1 will evaluate to 1 if there´s no .foo
       element in the input. It´s similar to how or is sometimes used in Python (jq´s or operator
       is reserved for strictly Boolean operations).

           jq ´.foo // 42´
              {"foo": 19}
           => 19

           jq ´.foo // 42´
           => 42

       Errors  can be caught by using try EXP catch EXP. The first expression is executed, and if
       it fails then the second is executed with the error message. The output of the handler, if
       any, is output as if it had been the output of the expression to try.

       The try EXP form uses empty as the exception handler.

           jq ´try .a catch ". is not an object"´
           => ". is not an object"

           jq ´[.[]|try .a]´
              [{}, true, {"a":1}]
           => [null, 1]

           jq ´try error("some exception") catch .´
           => "some exception"

   Breaking out of control structures
       A  convenient use of try/catch is to break out of control structures like reduce, foreach,
       while, and so on.

       For example:

           # Repeat an expression until it raises "break" as an
           # error, then stop repeating without re-raising the error.
           # But if the error caught is not "break" then re-raise it.
           try repeat(exp) catch .=="break" then empty else error;

       jq has a syntax for named lexical labels to "break" or "go (back) to":

           label $out | ... break $out ...

       The break $label_name expression will cause the program to to act as  though  the  nearest
       (to the left) label $label_name produced empty.

       The relationship between the break and corresponding label is lexical: the label has to be
       "visible" from the break.

       To break out of a reduce, for example:

           label $out | reduce .[] as $item (null; if .==false then break $out else ... end)

       The following jq program produces a syntax error:

           break $out

       because no label $out is visible.

   ? operator
       The ? operator, used as EXP?, is shorthand for try EXP.

           jq ´[.[]|(.a)?]´
              [{}, true, {"a":1}]
           => [null, 1]


       jq uses the Oniguruma regular expression library, as do php, ruby, TextMate, Sublime Text,
       etc, so the description here will focus on jq specifics.

       The jq regex filters are defined so that they can be used using one of these patterns:

           STRING | FILTER( REGEX )
           STRING | FILTER( [REGEX] )
           STRING | FILTER( [REGEX, FLAGS] )

       where:  * STRING, REGEX and FLAGS are jq strings and subject to jq string interpolation; *
       REGEX, after string interpolation, should be a valid PCRE regex; * FILTER is one of  test,
       match, or capture, as described below.

       FLAGS is a string consisting of one of more of the supported flags:

       •   g - Global search (find all matches, not just the first)

       •   i - Case insensitive search

       •   m - Multi line mode (´.´ will match newlines)

       •   n - Ignore empty matches

       •   p - Both s and m modes are enabled

       •   s - Single line mode (´^´ -> ´\A´, ´$´ -> ´\Z´)

       •   l - Find longest possible matches

       •   x - Extended regex format (ignore whitespace and comments)

       To match whitespace in an x pattern use an escape such as \s, e.g.

       •   test( "a\sb", "x" ).

       Note that certain flags may also be specified within REGEX, e.g.

       •   jq -n ´("test", "TEst", "teST", "TEST") | test( "(?i)te(?-i)st" )´

       evaluates to: true, true, false, false.

   [Requires 1.5] test(val), test(regex; flags)
       Like  match,  but does not return match objects, only true or false for whether or not the
       regex matches the input.

           jq ´test("foo")´
           => true

           jq ´.[] | test("a b c # spaces are ignored"; "ix")´
              ["xabcd", "ABC"]
           => true, true

   [Requires 1.5] match(val), match(regex; flags)
       match outputs an object for each match it finds. Matches have the following fields:

       •   offset - offset in UTF-8 codepoints from the beginning of the input

       •   length - length in UTF-8 codepoints of the match

       •   string - the string that it matched

       •   captures - an array of objects representing capturing groups.

       Capturing group objects have the following fields:

       •   offset - offset in UTF-8 codepoints from the beginning of the input

       •   length - length in UTF-8 codepoints of this capturing group

       •   string - the string that was captured

       •   name - the name of the capturing group (or null if it was unnamed)

       Capturing groups that did not match anything return an offset of -1

           jq ´match("(abc)+"; "g")´
              "abc abc"
           => {"offset": 0, "length": 3, "string": "abc", "captures": [{"offset": 0, "length": 3, "string": "abc", "name": null}]}, {"offset": 4, "length": 3, "string": "abc", "captures": [{"offset": 4, "length": 3, "string": "abc", "name": null}]}

           jq ´match("foo")´
              "foo bar foo"
           => {"offset": 0, "length": 3, "string": "foo", "captures": []}

           jq ´match(["foo", "ig"])´
              "foo bar FOO"
           => {"offset": 0, "length": 3, "string": "foo", "captures": []}, {"offset": 8, "length": 3, "string": "FOO", "captures": []}

           jq ´match("foo (?<bar123>bar)? foo"; "ig")´
              "foo bar foo foo  foo"
           => {"offset": 0, "length": 11, "string": "foo bar foo", "captures": [{"offset": 4, "length": 3, "string": "bar", "name": "bar123"}]}, {"offset": 12, "length": 8, "string": "foo  foo", "captures": [{"offset": -1, "length": 0, "string": null, "name": "bar123"}]}

           jq ´[ match("."; "g")] | length´
           => 3

   [Requires 1.5] capture(val), capture(regex; flags)
       Collects the named captures in a JSON object, with the name of each capture  as  the  key,
       and the matched string as the corresponding value.

           jq ´capture("(?<a>[a-z]+)-(?<n>[0-9]+)")´
           => { "a": "xyzzy", "n": "14" }

   [Requires 1.5] scan(regex), scan(regex; flags)
       Emit  a  stream  of  the  non-overlapping  substrings of the input that match the regex in
       accordance with the flags, if any have been specified. If there is no match, the stream is
       empty.  To  capture  all the matches for each input string, use the idiom [ expr ], e.g. [
       scan(regex) ].

   split(regex; flags)
       For backwards compatibility, split splits on a string, not a regex.

   [Requires 1.5] splits(regex), splits(regex; flags)
       These provide the same results as their split counterparts, but as a stream instead of  an

   [Requires 1.5] sub(regex; tostring) sub(regex; string; flags)
       Emit  the  string  obtained by replacing the first match of regex in the input string with
       tostring, after interpolation. tostring should be a jq string, and may contain  references
       to  named  captures.  The  named  captures  are, in effect, presented as a JSON object (as
       constructed by capture) to tostring, so a reference to a captured variable named "x" would
       take the form: "(.x)".

   [Requires 1.5] gsub(regex; string), gsub(regex; string; flags)
       gsub  is like sub but all the non-overlapping occurrences of the regex are replaced by the
       string, after interpolation.


       Variables are an absolute necessity in most programming languages, but  they´re  relegated
       to an "advanced feature" in jq.

       In most languages, variables are the only means of passing around data. If you calculate a
       value, and you want to use it more than once, you´ll need to store it in  a  variable.  To
       pass  a  value  to  another  part  of the program, you´ll need that part of the program to
       define a variable (as a function parameter, object member, or whatever) in which to  place
       the data.

       It is also possible to define functions in jq, although this is is a feature whose biggest
       use is defining jq´s standard library (many jq functions such as map and find are in  fact
       written in jq).

       jq  has  reduction  operators,  which are very powerful but a bit tricky. Again, these are
       mostly used internally, to define some useful bits of jq´s standard library.

       It may not be obvious at first, but jq is all about generators (yes,  as  often  found  in
       other languages). Some utilities are provided to help deal with generators.

       Some  minimal  I/O  support (besides reading JSON from standard input, and writing JSON to
       standard output) is available.

       Finally, there is a module/library system.

       In jq, all filters have an input and an output, so manual plumbing  is  not  necessary  to
       pass a value from one part of a program to the next. Many expressions, for instance a + b,
       pass their input to two distinct subexpressions (here a and b are  both  passed  the  same
       input), so variables aren´t usually necessary in order to use a value twice.

       For  instance,  calculating  the  average  value  of  an  array  of numbers requires a few
       variables in most languages - at least one to hold the array, perhaps one for each element
       or  for  a loop counter. In jq, it´s simply add / length - the add expression is given the
       array and produces its sum, and the length expression is given the array and produces  its

       So,  there´s generally a cleaner way to solve most problems in jq than defining variables.
       Still, sometimes they do make things  easier,  so  jq  lets  you  define  variables  using
       expression as $variable. All variable names start with $. Here´s a slightly uglier version
       of the array-averaging example:

           length as $array_length | add / $array_length

       We´ll need a more complicated problem to find a situation where using  variables  actually
       makes our lives easier.

       Suppose  we  have  an  array  of blog posts, with "author" and "title" fields, and another
       object which is used to map author usernames to real names. Our input looks like:

           {"posts": [{"title": "Frist psot", "author": "anon"},
                      {"title": "A well-written article", "author": "person1"}],
            "realnames": {"anon": "Anonymous Coward",
                          "person1": "Person McPherson"}}

       We want to produce the posts with the author field containing a real name, as in:

           {"title": "Frist psot", "author": "Anonymous Coward"}
           {"title": "A well-written article", "author": "Person McPherson"}

       We use a variable, $names, to store the realnames object, so that we can refer to it later
       when looking up author usernames:

           .realnames as $names | .posts[] | {title, author: $names[.author]}

       The  expression  exp  as $x | ... means: for each value of expression exp, run the rest of
       the pipeline with the entire original input, and with  $x  set  to  that  value.  Thus  as
       functions as something of a foreach loop.

       Just  as  {foo} is a handy way of writing {foo: .foo}, so {$foo} is a handy way of writing

       Multiple variables may be declared using a single as expression  by  providing  a  pattern
       that matches the structure of the input (this is known as "destructuring"):

           . as {realnames: $names, posts: [$first, $second]} | ...

       The  variable  declarations  in  array patterns (e.g., . as [$first, $second]) bind to the
       elements of the array in from the element at index zero on up, in order. When there is  no
       value at the index for an array pattern element, null is bound to that variable.

       Variables are scoped over the rest of the expression that defines them, so

           .realnames as $names | (.posts[] | {title, author: $names[.author]})

       will work, but

           (.realnames as $names | .posts[]) | {title, author: $names[.author]}


       For  programming  language  theorists,  it´s  more  accurate  to say that jq variables are
       lexically-scoped bindings. In particular there´s no way to change the value of a  binding;
       one  can  only setup a new binding with the same name, but which will not be visible where
       the old one was.

           jq ´.bar as $x | .foo | . + $x´
              {"foo":10, "bar":200}
           => 210

           jq ´. as $i|[(.*2|. as $i| $i), $i]´
           => [10,5]

           jq ´. as [$a, $b, {c: $c}] | $a + $b + $c´
              [2, 3, {"c": 4, "d": 5}]
           => 9

           jq ´.[] as [$a, $b] | {a: $a, b: $b}´
              [[0], [0, 1], [2, 1, 0]]
           => {"a":0,"b":null}, {"a":0,"b":1}, {"a":2,"b":1}

   Defining Functions
       You can give a filter a name using "def" syntax:

           def increment: . + 1;

       From then on, increment is usable as a filter just like a builtin function (in fact,  this
       is how some of the builtins are defined). A function may take arguments:

           def map(f): [.[] | f];

       Arguments  are  passed  as  filters,  not  as  values. The same argument may be referenced
       multiple times with different inputs (here f is run for each element of the input  array).
       Arguments  to  a  function  work  more  like  callbacks than like value arguments. This is
       important to understand. Consider:

           def foo(f): f|f;

       The result will be 20 because f is .*2, and during the first invocation of f . will be  5,
       and  the  second  time it will be 10 (5 * 2), so the result will be 20. Function arguments
       are filters, and filters expect an input when invoked.

       If you want the value-argument behaviour for defining simple functions, you can just use a

           def addvalue(f): f as $f | map(. + $f);

       Or use the short-hand:

           def addvalue($f): ...;

       With  either  definition,  addvalue(.foo)  will add the current input´s .foo field to each
       element of the array.

       Multiple definitions using the same function name are allowed. Each re-definition replaces
       the  previous  one for the same number of function arguments, but only for references from
       functions (or main program) subsequent to the re-definition.

           jq ´def addvalue(f): . + [f]; map(addvalue(.[0]))´
           => [[1,2,1], [10,20,10]]

           jq ´def addvalue(f): f as $x | map(. + $x); addvalue(.[0])´
           => [[1,2,1,2], [10,20,1,2]]

       The reduce syntax in jq allows you to combine all of  the  results  of  an  expression  by
       accumulating  them  into  a  single  answer.  As  an  example,  we´ll pass [3,2,1] to this

           reduce .[] as $item (0; . + $item)

       For each result that .[] produces, . +  $item  is  run  to  accumulate  a  running  total,
       starting  from  0. In this example, .[] produces the results 3, 2, and 1, so the effect is
       similar to running something like this:

           0 | (3 as $item | . + $item) |
               (2 as $item | . + $item) |
               (1 as $item | . + $item)

           jq ´reduce .[] as $item (0; . + $item)´
           => 20

   limit(n; exp)
       The limit function extracts up to n outputs from exp.

           jq ´[limit(3;.[])]´
           => [0,1,2]

   first(expr), last(expr), nth(n; expr)
       The first(expr) and last(expr) functions extract the first  and  last  values  from  expr,

       The  nth(n;  expr)  function extracts the nth value output by expr. This can be defined as
       def nth(n; expr): last(limit(n + 1;  expr));.  Note  that  nth(n;  expr)  doesn´t  support
       negative values of n.

           jq ´[first(range(.)), last(range(.)), nth(./2; range(.))]´
           => [0,9,5]

   first, last, nth(n)
       The first and last functions extract the first and last values from any array at ..

       The nth(n) function extracts the nth value of any array at ..

           jq ´[range(.)]|[first, last, nth(5)]´
           => [0,9,5]

       The  foreach  syntax is similar to reduce, but intended to allow the construction of limit
       and reducers that produce intermediate results (see example).

       The form is foreach EXP as $var (INIT; UPDATE; EXTRACT). Like reduce,  INIT  is  evaluated
       once  to  produce  a  state  value,  then  each  output of EXP is bound to $var, UPDATE is
       evaluated for each output of EXP with the current state and with $var visible. Each  value
       output  by  UPDATE replaces the previous state. Finally, EXTRACT is evaluated for each new
       state to extract an output of foreach.

       This is mostly useful only for constructing reduce- and limit-like functions.  But  it  is
       much more general, as it allows for partial reductions (see the example below).

           jq ´[foreach .[] as $item ([[],[]]; if $item == null then [[],.[0]] else [(.[0] + [$item]),[]] end; if $item == null then .[1] else empty end)]´
           => [[1,2,3,4],["a","b"]]

       As  described  above,  recurse  uses  recursion, and any jq function can be recursive. The
       while builtin is also implemented in terms of recursion.

       Tail calls are optimized whenever the expression to the left of the recursive call outputs
       its  last  value.  In practice this means that the expression to the left of the recursive
       call should not produce more than one output for each input.

       For example:

           def recurse(f): def r: ., (f | select(. != null) | r); r;

           def while(cond; update):
             def _while:
               if cond then ., (update | _while) else empty end;

           def repeat(exp):
             def _repeat:
               exp, _repeat;

   Generators and iterators
       Some jq operators and functions are actually generators in that  they  can  produce  zero,
       one,  or  more  values  for  each  input,  just  as  one might expect in other programming
       languages that have generators. For example, .[] generates all the  values  in  its  input
       (which  must  be an array or an object), range(0; 10) generates the integers between 0 and
       10, and so on.

       Even the comma operator is a generator, generating  first  the  values  generated  by  the
       expression  to  the  left of the comma, then for each of those, the values generate by the
       expression on the right of the comma.

       The empty builtin  is  the  generator  that  produces  zero  outputs.  The  empty  builtin
       backtracks to the preceding generator expression.

       All  jq  functions can be generators just by using builtin generators. It is also possible
       to define new generators using only recursion and the comma  operator.  If  the  recursive
       call(s)  is(are)  "in  tail position" then the generator will be efficient. In the example
       below the recursive call by _range to itself is in tail position. The  example  shows  off
       three advanced topics: tail recursion, generator construction, and sub-functions.

           jq ´def range(init; upto; by): def _range: if (by > 0 and . < upto) or (by < 0 and . > upto) then ., ((.+by)|_range) else . end; if by == 0 then init else init|_range end | select((by > 0 and . < upto) or (by < 0 and . > upto)); range(0; 10; 3)´
           => 0, 3, 6, 9

           jq ´def while(cond; update): def _while: if cond then ., (update | _while) else empty end; _while; [while(.<100; .*2)]´
           => [1,2,4,8,16,32,64]


       jq currently only has IEEE754 double-precision (64-bit) floating point number support.

       Besides  simple  arithmetic  operators such as +, jq also has most standard math functions
       from the C math library. C math functions that take a single input argument (e.g.,  sin())
       are  available  as  zero-argument  jq  functions.  C  math  functions  that take two input
       arguments (e.g., pow()) are available as two-argument jq functions that ignore ..

       Availability of standard math functions depends on the availability of  the  corresponding
       math  functions  in  your  operating system and C math library. Unavailable math functions
       will be defined but will raise an error.


       At this time jq has minimal support for I/O, mostly in  the  form  of  control  over  when
       inputs are read. Two builtins functions are provided for this, input and inputs, that read
       from the same sources (e.g., stdin, files named on the command-line) as jq  itself.  These
       two builtins, and jq´s own reading actions, can be interleaved with each other.

       One  builtin  provides  minimal  output  capabilities,  debug. (Recall that a jq program´s
       output values are always output as JSON texts on  stdout.)  The  debug  builtin  can  have
       application-specific behavior, such as for executables that use the libjq C API but aren´t
       the jq executable itself.

       Outputs one new input.

       Outputs all remaining inputs, one by one.

       This is primarily useful for reductions over a program´s inputs.

       Causes a debug message based on the input value to be produced. The  jq  executable  wraps
       the  input  value  with ["DEBUG:", <input-value>] and prints that and a newline on stderr,
       compactly. This may change in the future.

       Returns the name of the file whose input is currently being filtered. Note that this  will
       not work well unless jq is running in a UTF-8 locale.

       Returns the line number of the input currently being filtered.


       With  the  --stream  option  jq  can parse input texts in a streaming fashion, allowing jq
       programs to start processing large JSON texts immediately  rather  than  after  the  parse
       completes. If you have a single JSON text that is 1GB in size, streaming it will allow you
       to process it much more quickly.

       However, streaming isn´t  easy  to  deal  with  as  the  jq  program  will  have  [<path>,
       <leaf-value>] (and a few other forms) as inputs.

       Several builtins are provided to make handling streams easier.

       The    examples    below    use   the   the   streamed   form   of   [0,[1]],   which   is

       Streaming forms include [<path>, <leaf-value>] (to indicate any scalar value, empty array,
       or  empty  object),  and  [<path>]  (to  indicate  the  end of an array or object). Future
       versions of jq run with --stream and -seq may output  additional  forms  such  as  ["error
       message"] when an input text fails to parse.

       Consumes  a  number  as input and truncates the corresponding number of path elements from
       the left of the outputs of the given streaming expression.

           jq ´[1|truncate_stream([[0],1],[[1,0],2],[[1,0]],[[1]])]´
           => [[[0],2],[[0]]]

       Outputs values corresponding to the stream expression´s outputs.

           jq ´fromstream(1|truncate_stream([[0],1],[[1,0],2],[[1,0]],[[1]]))´
           => [2]

       The tostream builtin outputs the streamed form of its input.

           jq ´. as $dot|fromstream($dot|tostream)|.==$dot´
           => true


       Assignment works a little differently in jq than in most programming languages. jq doesn´t
       distinguish  between  references  to  and  copies of something - two objects or arrays are
       either equal or not equal, without any further notion of being "the same object"  or  "not
       the same object".

       If  an  object has two fields which are arrays, .foo and .bar, and you append something to
       .foo, then .bar will not get bigger. Even if you´ve just set .bar = .foo. If  you´re  used
       to  programming  in languages like Python, Java, Ruby, Javascript, etc. then you can think
       of it as though jq does a full deep copy of every object before  it  does  the  assignment
       (for performance, it doesn´t actually do that, but that´s the general idea).

       All the assignment operators in jq have path expressions on the left-hand side.

       The  filter .foo = 1 will take as input an object and produce as output an object with the
       "foo" field set to 1. There is no notion of "modifying" or "changing" something  in  jq  -
       all jq values are immutable. For instance,

       .foo = .bar | .foo.baz = 1

       will  not  have the side-effect of setting .bar.baz to be set to 1, as the similar-looking
       program in Javascript, Python, Ruby or other languages would. Unlike these languages  (but
       like  Haskell  and  some  other functional languages), there is no notion of two arrays or
       objects being "the same array" or "the same object". They can be equal, or not equal,  but
       if we change one of them in no circumstances will the other change behind our backs.

       This  means  that  it´s  impossible to build circular values in jq (such as an array whose
       first element is itself). This is quite  intentional,  and  ensures  that  anything  a  jq
       program can produce can be represented in JSON.

       Note  that  the left-hand side of ´=´ refers to a value in .. Thus $ = 1 won´t work
       as expected ($ is not a valid or useful path expression in .); use $var | .foo =  1

       If  the  right-hand side of ´=´ produces multiple values, then for each such value jq will
       set the paths on the left-hand side to the value and then it will output the  modified  ..
       For  example,  (.a,.b)=range(2)  outputs  {"a":0,"b":0},  then {"a":1,"b":1}. The "update"
       assignment forms (see below) do not do this.

       Note too that .a,.b=0 does not set .a and .b, but (.a,.b)=0 sets both.

       As well as the assignment operator ´=´, jq provides  the  "update"  operator  ´|=´,  which
       takes  a  filter  on the right-hand side and works out the new value for the property of .
       being assigned to by running the old value through this expression. For instance, .foo  |=
       .+1 will build an object with the "foo" field set to the input´s "foo" plus 1.

       This example should show the difference between ´=´ and ´|=´:

       Provide input ´{"a": {"b": 10}, "b": 20}´ to the programs:

       .a = .b .a |= .b

       The  former will set the "a" field of the input to the "b" field of the input, and produce
       the output {"a": 20}. The latter will set the "a" field of the input to  the  "a"  field´s
       "b" field, producing {"a": 10}.

       The left-hand side can be any general path expression; see path().

       Note  that the left-hand side of ´|=´ refers to a value in .. Thus $ |= . + 1 won´t
       work as expected ($ is not a valid or useful path expression in .); use $var | .foo
       |= . + 1 instead.

       If the right-hand side outputs multiple values, only the last one will be used.

           jq ´(..|select(type=="boolean")) |= if . then 1 else 0 end´
           => [1,0,[5,1,[1,[0]],0]]

   +=, -=, *=, /=, %=, //=
       jq  has  a few operators of the form a op= b, which are all equivalent to a |= . op b. So,
       += 1 can be used to increment values.

           jq ´.foo += 1´
              {"foo": 42}
           => {"foo": 43}

   Complex assignments
       Lots more things are allowed on the left-hand  side  of  a  jq  assignment  than  in  most
       languages.  We´ve  already  seen  simple field accesses on the left hand side, and it´s no
       surprise that array accesses work just as well:

           .posts[0].title = "JQ Manual"

       What may come as a surprise is that the  expression  on  the  left  may  produce  multiple
       results, referring to different points in the input document:

           .posts[].comments |= . + ["this is great"]

       That  example  appends  the string "this is great" to the "comments" array of each post in
       the input (where the input is an object with a field "posts" which is an array of posts).

       When jq encounters an assignment like ´a = b´, it records the "path"  taken  to  select  a
       part of the input document while executing a. This path is then used to find which part of
       the input to change while executing  the  assignment.  Any  filter  may  be  used  on  the
       left-hand  side of an equals - whichever paths it selects from the input will be where the
       assignment is performed.

       This is a very powerful operation. Suppose we wanted to add a comment to blog posts, using
       the  same  "blog"  input above. This time, we only want to comment on the posts written by
       "stedolan". We can find those posts using the "select" function described earlier:

           .posts[] | select(.author == "stedolan")

       The paths provided by this operation point to each of the posts that "stedolan" wrote, and
       we can comment on each of them in the same way that we did before:

           (.posts[] | select(.author == "stedolan") | .comments) |=
               . + ["terrible."]


       jq has a library/module system. Modules are files whose names end in .jq.

       Modules  imported  by a program are searched for in a default search path (see below). The
       import and include directives allow the importer to alter this path.

       Paths in the a search path are subject to various substitutions.

       For paths starting with "~/", the user´s home directory is substituted for "~".

       For paths starting with "$ORIGIN/", the path of  the  jq  executable  is  substituted  for

       For  paths  starting  with  "./"  or paths that are ".", the path of the including file is
       substituted for ".". For  top-level  programs  given  on  the  command-line,  the  current
       directory is used.

       Import directives can optionally specify a search path to which the default is appended.

       The  default  search  path  is  the  search path given to the -L command-line option, else
       ["~/.jq", "$ORIGIN/../lib/jq", "$ORIGIN/../lib"].

       Null and empty string path elements terminate search path processing.

       A dependency with relative path "foo/bar"  would  be  searched  for  in  "foo/bar.jq"  and
       "foo/bar/bar.jq"  in the given search path. This is intended to allow modules to be placed
       in a directory along with, for example, version control files, README files,  and  so  on,
       but also to allow for single-file modules.

       Consecutive  components  with  the  same  name are not allowed to avoid ambiguities (e.g.,

       For example,  with  -L$HOME/.jq  a  module  foo  can  be  found  in  $HOME/.jq/foo.jq  and

       If "$HOME/.jq" is a file, it is sourced into the main program.

   import RelativePathString as NAME [<metadata>];
       Imports a module found at the given path relative to a directory in a search path. A ".jq"
       suffix will be added to the relative path string. The module´s symbols are  prefixed  with

       The  optional  metadata must be a constant jq expression. It should be an object with keys
       like "homepage" and so on. At this time  jq  only  uses  the  "search"  key/value  of  the
       metadata. The metadata is also made available to users via the modulemeta builtin.

       The  "search"  key in the metadata, if present, should have a string or array value (array
       of strings); this is the search path to be prefixed to the top-level search path.

   include RelativePathString [<metadata>];
       Imports a module found at the given path relative to a directory in a search path as if it
       were  included  in  place.  A  ".jq" suffix will be added to the relative path string. The
       module´s symbols are imported into the caller´s namespace as if the module´s  content  had
       been included directly.

       The  optional  metadata must be a constant jq expression. It should be an object with keys
       like "homepage" and so on. At this time  jq  only  uses  the  "search"  key/value  of  the
       metadata. The metadata is also made available to users via the modulemeta builtin.

   import RelativePathString as $NAME [<metadata>];
       Imports  a  JSON  file found at the given path relative to a directory in a search path. A
       ".json" suffix will be added to  the  relative  path  string.  The  file´s  data  will  be
       available as $NAME::NAME.

       The  optional  metadata must be a constant jq expression. It should be an object with keys
       like "homepage" and so on. At this time  jq  only  uses  the  "search"  key/value  of  the
       metadata. The metadata is also made available to users via the modulemeta builtin.

       The  "search"  key in the metadata, if present, should have a string or array value (array
       of strings); this is the search path to be prefixed to the top-level search path.

   module <metadata>;
       This directive is entirely optional. It´s not required for  proper  operation.  It  serves
       only the purpose of providing metadata that can be read with the modulemeta builtin.

       The  metadata  must  be  a  constant  jq expression. It should be an object with keys like
       "homepage". At this time jq doesn´t use this metadata, but it is made available  to  users
       via the modulemeta builtin.

       Takes  a  module  name  as  input and outputs the module´s metadata as an object, with the
       module´s imports (including metadata) as an array value for the "deps" key.

       Programs can use this to query a module´s metadata, which they  could  then  use  to,  for
       example, search for, download, and install missing dependencies.


       Presumably. Report them or discuss them at:



       Stephen Dolan <>

                                           October 2015                                     JQ(1)